Active Learning for Regression by Inverse Distance Weighting

This paper proposes an active learning (AL) algorithm to solve regression problems based on inverse-distance weighting functions for selecting the feature vectors to query. The algorithm has the following features: (i) supports both pool-based and population-based sampling; (ii) it is not tailored to a particular class of predictors; (iii) can handle known and unknown constraints on the queryable feature vectors; and (iv) can run either sequentially, or in batch mode, depending on how often the predictor is retrained. The potentials of the method are shown in numerical tests on illustrative synthetic problems and real-world datasets from the UCI repository. A Python implementation of the algorithm, that we call IDEAL (Inverse-Distance based Exploration for Active Learning), is available at \url{http://cse.lab.imtlucca.it/~bemporad/ideal}.